Question

The half-life of 14C is 5,730 years. If a sample contained 100 percent 14C and 0 percent 14N at a point in time 17,190 years ago, then what percentage of 14C would it contain today

Answer 1

The time taken by a radioactive substance to decay to half of its original mass is termed as half-life.

So,number of half-lives

50 percent of initial mass - after 1 half life

25 percent of initial mass - after 2 half lives

12.5 percent of initial mass - after 3 half lives

6.25 percent of initial mass - after 4 half lives.

According to data given, the origin of sample was years ago and half-life is 5730 years. So, the number of completed half-lives is 17190/5730=3 .

Thus, 12.5 percent of 14C is present today.